We're going to take these concepts [from the previous article] further and add a new one: REST. In the course of this series so far, we've only been discussing how to use the Router to examine and act on different parts of a URL.

He gives a list of possible headers that could come from a client (like Accept-Charset or Content-Type) and how these can be directly pulled in to the CakePHP routing system. A few extra bits of code later and your app can be mapping requests directly to the controllers for the actions the user's requesting. All that's left is to serialize the results back into XML to echo out.